I had this happen 3 times tonight while working on a plain text document with minimal graphics. The problem you describe with the program telling you it is currently only available to your username is called a Data Lock. Essentially, the program thinks the
document is still open and won't let two users try to change it at the same time. The surefire way to clear the data lock is a reboot. Unfortunately, with Word hung, Windows 7 won't reboot correctly either and it takes a hard power down to get it to happen
for me.
As to the lost changes, I thought that was the case until I started poking around. Instead of prompting you with the last autosave, Word 10 just quietly tucks it away and you have to dig for it. After opening the document, click the "File" tab and look through
the "versions" of the document on the bottom left for the most recent autosave. Your manual save may still be more recent.
A bad workaround is simply to turn off the autosave. Part of my pay is based on turnaround time on the documents I work on, so I can't afford to be constantly rebooting and recovering where I was in the document. A better solution for me is to turn off the
autosave since that is what is crashing the program. I can work through it that way, but I'm wondering if Microsoft would back me down to a more stable Office 7 until they figure out this program killer.